Electroacoustic transducers, such as a headphone set and a speaker, are known to convert electric signals into sound. Such an electroacoustic transducer includes a baffle holding a diaphragm. The baffle has a through hole extending in the thickness direction (hereinafter also referred to as rearward direction) of the baffle to release sound emitted from the diaphragm in the rearward direction, and thus preventing distortion of the diaphragm. Such an electroacoustic transducer generates reduced acoustic resistance components in the sound emitting direction or frontward direction of the diaphragm to achieve stable operation of the diaphragm.
The electroacoustic transducer also includes an acoustic resistor disposed over the through hole of the baffle and having frequency-dependent attenuation characteristics. The acoustic resistor generates a resistance while sound is passing through the through hole, thus improving the operation of the diaphragm in response to a specific frequency. The electroacoustic transducer having such a design achieves a smooth frequency response of a driver unit including a driver and a diaphragm.
Unfortunately, the electroacoustic transducer having such a structure has a difficulty in achieving a smooth frequency response over a wide bandwidth to a variety of sound levels having different wavelengths.
Japanese Unexamined Patent Application Publication No. 2011-087993 (Patent Literature 1), for example, discloses a headphone set including a first hole to release air inside a rear air chamber to the external space and a second hole to release air inside a front air chamber to the external space.
The headphone set disclosed in Patent Literature 1 also has a difficulty in achieving a smooth frequency response over a wide bandwidth.